An implant is provided which enhances structural stability across a joint between a first and a second bone to be immobilized. The implant comprises a first and a second element, wherein the first element comprises a proximal, a distal and an intermediate section. The front end of the implant is formed as a pointed head with structures enabling the implant to penetrate bone material, including a channel-like structure running from the front end to a reservoir in the intermediate section. The reservoir is provided for receiving bone material through the channel-like structure and distributing it into a space between two bones upon placing the implant into the bones. A tool is provided for placing the implant into two bones, wherein the tool has means for connecting it to structures in the first element and the second element, so that the two elements can be moved independently.